/Engine/Source/Runtime/HeadMountedDisplay/Public/IXRTrackingSystem.h
Same as IsHeadTrackingAllowed, but returns false if the World is not using VR (such as with the non-VR PIE instances when using VR Preview)
virtual bool IsHeadTrackingAllowedForWorld ( [UWorld](API\Runtime\Engine\Engine\UWorld) & World ) const